glsl: move some lowering to the compiler

Rather than doing this lowering potentially multiple times when a
shader is relinked we can instead do it once in the compiler.

This change also gets us closer to converting to NIR at compile
time.

Reviewed-by: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27690>

src/compiler/glsl/glsl_parser_extras.cpp

@@ -2193,6 +2193,7 @@ do_late_parsing_checks(struct _mesa_glsl_parse_state *state)
 
 static void
 opt_shader_and_create_symbol_table(const struct gl_constants *consts,
+                                   const struct gl_extensions *exts,
                                    struct glsl_symbol_table *source_symbols,
                                    struct gl_shader *shader)
 {
@@ -2229,6 +2230,17 @@ opt_shader_and_create_symbol_table(const struct gl_constants *consts,
 
    optimize_dead_builtin_variables(shader->ir, other);
 
+   lower_vector_derefs(shader);
+
+   lower_packing_builtins(shader->ir, exts->ARB_shading_language_packing,
+                          exts->ARB_gpu_shader5,
+                          consts->GLSLHasHalfFloatPacking);
+   do_mat_op_to_vec(shader->ir);
+
+   lower_instructions(shader->ir, exts->ARB_gpu_shader5);
+
+   do_vec_index_to_cond_assign(shader->ir);
+
    validate_ir_tree(shader->ir);
 
    /* Retain any live IR, but trash the rest. */
@@ -2399,7 +2411,8 @@ _mesa_glsl_compile_shader(struct gl_context *ctx, struct gl_shader *shader,
       lower_builtins(shader->ir);
       assign_subroutine_indexes(state);
       lower_subroutine(shader->ir, state);
-      opt_shader_and_create_symbol_table(&ctx->Const, state->symbols, shader);
+      opt_shader_and_create_symbol_table(&ctx->Const, &ctx->Extensions,
+                                         state->symbols, shader);
    }
 
    if (!force_recompile) {

src/compiler/glsl/ir_optimization.h

@@ -30,6 +30,7 @@
 #ifndef GLSL_IR_OPTIMIZATION_H
 #define GLSL_IR_OPTIMIZATION_H
 
+struct gl_shader;
 struct gl_linked_shader;
 struct gl_shader_program;
 
@@ -60,7 +61,7 @@ bool lower_packing_builtins(exec_list *instructions,
                             bool has_shading_language_packing,
                             bool has_gpu_shader5,
                             bool has_half_float_packing);
-bool lower_vector_derefs(gl_linked_shader *shader);
+bool lower_vector_derefs(gl_shader *shader);
 void optimize_dead_builtin_variables(exec_list *instructions,
                                      enum ir_variable_mode other);
 

src/compiler/glsl/linker.cpp

@@ -2919,17 +2919,6 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
       if (!prog->data->LinkStatus)
          goto done;
 
-      lower_vector_derefs(shader);
-
-      lower_packing_builtins(ir, ctx->Extensions.ARB_shading_language_packing,
-                             ctx->Extensions.ARB_gpu_shader5,
-                             ctx->Const.GLSLHasHalfFloatPacking);
-      do_mat_op_to_vec(ir);
-
-      lower_instructions(ir, ctx->Extensions.ARB_gpu_shader5);
-
-      do_vec_index_to_cond_assign(ir);
-
       const struct gl_shader_compiler_options *gl_options =
          &consts->ShaderCompilerOptions[i];
 

src/compiler/glsl/lower_vector_derefs.cpp

@@ -193,7 +193,7 @@ vector_deref_visitor::handle_rvalue(ir_rvalue **rv)
 }
 
 bool
-lower_vector_derefs(gl_linked_shader *shader)
+lower_vector_derefs(gl_shader *shader)
 {
    vector_deref_visitor v(shader->ir, shader->Stage);
 

src/compiler/glsl/tests/lower_precision_test.py

@@ -401,7 +401,7 @@ TESTS = [
              gl_FragColor = vec4(b * a, 0.0, 0.0);
          }
          """,
-         r'\(expression +f16vec2 \* \(var_ref b\) \(var_ref a\)'),
+         r'\(expression f16vec2 \+ \(expression f16vec2 \* \(array_ref \(var_ref b\) \(constant int \(0\)\) \) \(swiz x \(var_ref a\) \)\) \(expression f16vec2 \* \(array_ref \(var_ref b\) \(constant int \(1\)\) \) \(swiz y \(var_ref a\) \)\) \) \)'),
     Test("f32 simple struct deref",
          """
          precision mediump float;